Drill bit and rod coupling



June 28, 1966 0. P Ps 3,258,284

DRILL BIT AND ROD I9 g 9 INVENTOR. 2 ORVILLE PH PPS 91 BY m/ A ORNEY United States Patent 3,258,284 DRILL BIT AND ROD CGUILING Orville Phipps, 607 Interstate Trust Bldg, Denver, Colo. Filed Dec. 30, 1963, Ser. No. 334,117 4 Claims. (Cl. 287-425) This invention relates to drill bits percussively actuable through an associated rod to penetrate and establish bores within natural earth and other materials, and more particularly to the category of such facilities termed hammer drills utilized in relatively-moderat sizes under percussive influences to penetrate rock and analogous obdurate substances, and has as an object to provide a novel and improved coupling for the operative interassociation of a drill bit component and its actuating rod.

A further object of the invention is to provide a drill bit and rod coupling for the operative interassociation of a hammer bit and its coaxial actuating rod that enhances the efiicient transmission of impacts applied to the bit through the rod,

A further object of the invention is to provide a drill bit and rod coupling for the operative interassociation of a hammer bit and its coaxial actuating rod that is uniquely immune to deformation and impairment under prolonged subjection to repetitious impact transmission A further object of the invention is to provide a drill bit and rod coupling for the operative interassociation of a hammer bit and its coaxial actuating rod that preserves through long-extended use the facility of component interconnection and separation available therethrough.

A further object of the invention is to provide a drill bit and rod coupling of mating thread type that is characterized by a unique correlation of novel thread profiles advantageous for the operative interassociation of a hammer bit and its coaxial actuating rod.

A further object of the invention is to provid a drill bit and rod coupling of distinctive mating thread type especially suited for the operative interassociation of a hammer drill bit and its coaxial actuating rod that is expedient of production, feasibly variable in detail with maintenance of concept and principle for specific use adaptations, applicable to efficient attainment of its advantages as a feature of diverse bit and rod assemblies particular to a wide range of specialized operations, and promotive by virtue of its durability of operating and servicing economies.

With the foregoing and other objects in view, my invention consists in the construction, arrangement, and operative combination of elements as hereinafter set forth, pointed out in the appended claims, and illustr-ated by the accompanying drawing, in which FIGURE 1 is a side elevational view, partially in longitudinal section, of a hammer bit and the coacting end of an actuating rod as interrelated ready for use by the improved coupling of the present invention shown in a generally conventional relation of mating threads which excludes novelty of detail incapable of illustrating without distorting exaggeration.

FIGURE 2 is a fragmentary, radial half-section taken longitudinally of the threaded socket portion of the bit according to FIGURE 1 with corresponding exclusion of novel thread detail.

FIGURE 3 is a fragmentary, radial half-section taken longitudinally of the threaded stud portion of the rod end according to FIGURE 1 with corresponding exclusion of novel thread detail.

FIGURE 4 is a fragmentary view showing, partially in half-section, the mating coaction of the socket and stud components represented by FIGURES 2 and 3 with the novelties of thread detail exaggerated to facilitate explanation and enhance understanding.

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FIGURE 5 is a section transverse of the correlation according to FIGURE 4 taken substantially on the indicated line 5-5 of the last-named view with corresponding exaggeration of thread detail.

FIGURE 6 is a profile outline, on a much-enlarged scale, of the unique thread conformation primary to the instant invention and the mating correlations exaggerated in FIGURES 4 and 5.

Hammer drills as conventionally organized and extensively used for the development of bores penetrating rock and analogous materials characteristically include a generally-cylindrical bit 10 having a working face 11 of appropriate particularity substantially perpendicular to the longitudinal axis of the bit, a straight, rigid rod 12 suited for the transmission of axially-applied impacts, and means for detachably intercoupling the bit and rod in coaxial alignment to present the bit working face 11 exposed as a terminal of the assembly. Customarily supplied in multiple as integral units of varying lengths, the rods 12 connectible with and to actuate bits of diverse size and particularity are like formed at their ends remot from the bit attachment for reception in and coaction with the chuck of a hammer powered to apply impacts to and axially of the associated rod and to coincidentally rotate the associated rod, or to accommodate manual such rotation, during penetrative advance of the drill. Facilitating interchangeable operative association of the bit and rod components, the detachable intercoupling thereof is usually had by means of a mating thread joint formed to coaxially unite complementary stud and socket elements coaxial of the rod and bit in a manner to apply thread pitch of the joint with tightening effect upon the coupling in reaction to rod rotation which, quite commonly, is such as to establish a socalled left-hand pitch for the coupling threads. All of the foregoing is ordinary practice in the related art and in and of itself no part of the present invention save as environment essential to an understanding thereof and advantageously practical to benefit therefrom.

Occasion for the frequent interchange of bit and rod components during hammer drill operations emphasizes the practical importance of a bit and rod coupling which, while firm and secure during use of the coupled assembly, is readily separable and reconnectible at the site of use without delay and resort to specialized tools and equipment while effective, when conditioned for use of the drill, to efliciently transmit to the bit the impacts applied to the rod. Obviously, any and very coupling applied to connect the bit and rod components of a hammer drill is itself vulnerable to the impacts, and the effects thereof, manifest in and through the rod which act upon and are reflected through the coacting convolutions of a mating thread joint with consequent battering, deformation, and distortion of the threads conducive to impairment of impact transmission, inability of rod rotation to function for obviation of looseness developed in the joint, resistance to separation and reconnection of the joint components, and loss of much of the useful life of the sodamaged complements. With recognition of the attributes requisite for a drill bit and rod coupling of improved capability substantially immune to the adverse influences of sustained and repetitious use, the instant invention is directed to the provision of a unique mating thread joint distinguished by a novel thread profil which qualifies the complementary threads of the joint to conv sistently accomplish their coupling function with substantial immunity to damage or deformation.

As is customary practice, the improved coupling of the invention i effective to coaxially conjoin for separation and reconnection a stud 13 extending in axial alignment with and from one end of the typical rod 12 and a socket cavity within and opening through the free end of a sleeve 14 concentric with and directed away from the working face 11 of the bit 10. For purposes of illustration and description, only, the stud 13 is represented as carried by the rod and the sleeve 14 as integrated with the bit, but it is to be understood, as should be manifest, that the dispositions of the stud and sleeve could expediently be reversed to locate the stud as an integral extension of the bit and the sleeve as a socketed terminal of the rod without in any way altering the concept, nature, or structural organization of the improvement hereinafter detailed.

A feature of the improved coupling is the provision at the end of the sleeve 14, wherever carried, of a plane, annu-lar area 15 perpendicular to the axis of the socket concentnic with and about the open outer end thereof and the formation at and about the conjunction of the stud 13 with its coaxial component of a like plane, annular area 16 perpendicular to the axis of the stud adapted to complement and coactively engage the area 15 when the stud is fully entered in the sleeve socket for coaxial alignment of the bit and rod. When, as illustrated, the stud 13 is carried by the rod 12, the end of the latter mounting the stud may be radially expanded, as by upsetting, to the form of a boss 17 sized to present the area 16 as a terminal shoulder congruent with the area 15.

In broad analogy with a conventional practice, reception and retention of the stud 13 within the socket of the sleeve 14 for operative coalignment of the bit and rod 11 with the annular areas and 16 directly and closely interengaged is had through the agency of mating screw thread which, in accordance with the principles and for realization of the advantages of the instant invention, complete the improved coupling in a unique specific thread conformation and operative correlation. Pitched as regular spiral convolutions in a direction effective to apply relative operative rotation of the rod 12 to tighten the joint holding the areas 15 and 16 in close interengagement, the female thread component of the socket and the male thread component of the stud are identical as to complemenary profile and differ slighly in pitch diameter for a loose, non-binding coaction Wedgingly firmed and secured only when the areas 15 and 16 are solidly in contact. Naturally proportioned to the diameters of the components thereby joined, the thread complements distinguishing the coupling of the invention preferably are relatively coarse with but few turns per inch of axial length, are symmetrically cylindrical about the axis of the associated component, and function with intended advantage through and by virtue of the distinctive profile detailed with some exaggeration in FIGURE 6. As clearly appears in the profile diagram, the thread crests 18 of both complements, male and female, are semicircular to a radius R appropriate for development of the desired thread in a joint of given diameter, the thread roots 19 are U-shaped and define between opposed quadrantal arcs to the radius R at flat, spiral fillet 20 about and parallel to the axis of the component in a width R/N established by a slight spacing apart of the centers for the radii of the quadrantal arcs, such spacing being on the order of a few hundredths of an inch, and the crest and root arcs of each thread convolution are smoothly and tangentially conjoined by a flat, spiral band 21 in a width R/N radial of the component determined by a separation radially of the component of the locus for the centers of the crest radii outwardly with respect to the loci for the centers of the quadrantal arc radii, which separation, again on the order of a few hundredths of an inch, may well approximate one-half the width of the fillet 20. Identically profiled as represented and just described, the male and female complements of the joint thread are unlike in diameter and differ by a few thousandths of an inch to accommodate a free, slightly loose coaction of the smaller male thread with the female thread in the non-binding relationship indicated with considerable exaggeration by FIG. 5. Applied to the intercoupling of a one and three-fourths inch rod 12 with a four inch bit 11) a male thread having a crest diameter of one and three-fourths inches pitched two and one-half turns to the inch in a left-hand direction and profiled for coaction with an identical female thread five one-thousands larger in root diameter was characterized by an R value of eighteen one-hundredths of an inch, a width for the fillet 2d of four one-hundredths of an inch, and a width for the band 21 of two one-hundredths of an inch. As so dimensioned and proportioned, the mating threads of the coupling functioned successfully to realize all of the advantages and purposes of the invention through consequent interclamping of like annular areas 15 and 16 having major diameters of two and onehalf inches and radial widths of three-eighths of an inch.

identically profiled with a slight, but definite, diametric clearance as set forth, the male and female threads of the improved coupling freely mate in a loose coaction that separably connects the stud 13 in and with the socket of the sleeve 14 and serves to hold said components of the coupling against relative axial displacement subject to slight relative axial and diametric interplay. Relative rotation of the thread-coupled components in the direction appropriate to fully enter the stud within the sleeve socket ultimately interengages the areas 15 and 16 with consequent firming and tightening of the thread joint, since, as exaggerated in the showing of FIGURE 4, relative rotation of the components 10 and 12 continued after close abutment of the areas 15 and 16 arrests penetrative advance of the stud within the socket effects a wedging coaction of the bands 21 opposed by the like male and female thread profiles at that side of each thread complement directed inwardly of the associated component. Such wedging of the bands 21 securely clamps the stud to a seat in the socket that is determined and reflected by tight interengagement of the areas 15 and 16 maintained, as should be obvious, by rotation of the rod 12 and its stud 13 incident to operation of the hammer drill assembly in a joint-tightening direction; such wedging of the bands 21 also serving to space and hold separated the bands 21 on the opposite, or outwardly-directed, sides of the thread complements, as exemplified by the showing of FIGURE 4. As so organized and coupled for use, impacts applied axially of the rod 12 are transmitted through the clamp-abutted areas 15 and 16 directly to the bit 10 with high operative efficiency and minimal effect upon the coupling wherein, as is readily apparent, any impact-induced increase of stud penetration within the socket of the sleeve is accommodated by the separation of the thread complement sides remote from the incidence of the applied force and reflected by a loosening of the wedging coaction of the bands 21 at the other sides of the thread complements, all with avoidance of battering and deformation of the coupling threads, while any sooccasioned loosening of the thread joint characteristic of the coupling is promptly corrected to again solidly conjoin the areas 15 and 16 as the drill rod 12 is conventionally rotated as an incident of hammer drill operation.

It is feasible to provide, as illustrated, a transverselyconcave, annular fillet 22 at and concentrically about the conjunction of the stud 13 and annular area 16 complementary to and for centering coaction upon interengagement of the areas 15 and 16 with a transverselyconvex, annular lip 23 at and about the intersection of the sleeve socket with the area 15, whereby to assure registration of the areas 15 and 16 despite the radial clearance between the male and female complements of the thread joint, and conventional provision for the circulation of scavenging and cooling fluids through the hammer drill assembly is typified by the showing of an axial bore 24 opening through the rod 12 and stud 13 for delivery to a chamber 25 interiorly of the bit 14 serving outlets, not shown, through the working face 11 of the bit.

Since, as above noted, the stud 13 may be carried by the bit as well as by the rod 12 for cooperation with a socket in a sleeve 14 projecting from the rod 12 rather than from the bit, and since other changes, variations, and modifications in the form, construction, and arrangement of the features and elements shown and described may be had, all without departing from the spirit of my invention, I wish to be understood as being limited solely by the scope of the appended claims, rather than by any details of the illustrative showing and foregoing description.

I claim as my invention:

1. A percussively-actuable impact assembly comprising coaxial drill bit and rod components, one of said components including a socket having a flat, annular area perpendicular to the axis of said assembly and surrounding the open end of said socket, the other of said components including a stud received in said socket and having :a flat, annular area perpendicular to the axis of said assembly and surrounding the end of said stud adjacent to the remainder of its associated component, said annular area on said one component abuttingly engaging said annular area on said other component for direct transmission of impacts axially of said assembly, a thread joint separably interconnecting said components, said joint including complementary thread means carried interiorly of said socket and exteriorly of said stud, each of said thread means including alternate crest and root portions defining spiral thread convolutions, said root portions of said thread means on said socket and said crest portions of said thread means on said stud each defining a right-cylinder, the diameter of said cylinder defined by said root portions of said thread means on said socket being slightly greater than the diameter of said cylinder defined by said crest portions of said thread means on said stud whereby said complementary thread means coact with a slight radial clearance, the width of said root portions of said thread means on both said socket and said stud exceeding the width of said crest portions of said thread means whereby said complementary thread means coact with a slight axial clearance on one side of contiguous thread convolutions to permit slight axial movement under impact without contact between juxtaposed portions of said complementary thread means, a flat spiral band extending radially of the axis of said assembly on both sides of said thread convolutions of said complementary thread means and joining the crest portions of each thread means with the root portions of the same thread means, the spiral band on one thread means Wedgingly engaging the spiral band on the other thread means to define a secure engagement between said components, an arcuate, annular fillet carried by one of said components at the termination of its thread means adjacent its annular area, and a complementary arcuate, annular lip carried by the other of said components at the termination of its thread means adjacent its annular area, said lip abuttingly engaging said fillet to axially center said stud in said socket, said complementary thread means, said annular areas, said spiral bands and said fillet and lip being so constructed and arranged as to permit slight axial play between contiguous thread convolutions of said complementary thread means under impact while providing a wedging action between said spiral bands, an abutting contact between said annular areas and a coaction between said fillet and lip to secure said components against angular displacement and to center said components with respect to each other.

2. The impact assembly according to claim 1 wherein said complementary thread means are of like sinuous profile, said crest portions being substantially semi-circular and said root portions being substantially U-shaped, the width of said root portions exceeding the diameter of said semi-circular crest portions.

3. The impact assembly according to claim 2 wherein said U-shaped root portions include contiguous reversed arcs spaced apart by a flat fillet spirally concentric with the axis of said assembly.

4. The impact assembly according to claim 3 wherein said radial, flat spiral bands tangentially interconnect opposite sides of said semi circular crest portions with associated reversed arcs of said root portions.

References Cited by the Examiner UNITED STATES PATENTS 47,555 5/1865 Lecky 285-390 138,277 4/ 1873 Peet 285-390 X 1,642,183 9/1927 Thruston 287-125 X 1,642,285 9/ 1927 Woodward -46 1,777,481 10/1930 Black 285-390 X 1,851,714 3/1932 McCullough 285-390 1,973,848 9/1934 Duffy 285-333 X 2,052,019 8/1936 Baker 287- 2,569,275 9/1951 Baker 287-119 2,606,778 8/1952 Myhre 287-125 2,937,891 5/ 1960 Gressel 285-390 X CARL W. TOMLIN, Primary Examiner. I. B. TALTON, D. AROLA, Assistant Examiners, 

1. A PERCUSSIVELY-ACTUABLE IMPACT ASSEMBLY COMPRISING COAXIAL DRILL BIT AND ROD COMPONENTS, ONE OF SAID COMPONENTS INCLUDING A SOCKET HAVING A FLAT, ANNULAR AREA PERPENDICULAR TO THE AXIS OF SAID ASSEMBLY AND SURROUNDING THE OPEN END OF SAID SOCKET, THE OTHER OF SAID COMPONENTS INCLUDING A STUD RECEIVED IN SAID SOCKET AND HAVING A FLAT, ANNULAR AREA PERPENDICULAR TO THE AXIS OF SAID ASSEMBLY AND SURROUNDING THE END OF SAID STUD ADJACENT TO THE REMAINDER OF ITS ASSOCIATED COMPONENT, SAID ANNULAR AREA ON SAID ONE COMPONENT ABUTTINGLY ENGAGING SAID ANNULAR AREA ON SAID OTHER COMPONENT FOR DIRECT TRANSMISSION OF IMPACTS AXIALLY OF SAID ASSEMBLY, A THREAD JOINT SEPARABLY INTERCONNECTING SAID COMPONENTS, SAID JOINT INCLUDING COMPLEMENTARY THREAD MEANS CARRIED INTERIORLY OF SAID SOCKET AND EXTERIORLY OF SAID STUD, EACH OF SAID THREAD MEANS INCLUDING ALTERNATE CREST AND ROOT PORTIONS DEFINING SPIRAL THREAD CONVOLUTIONS, SAID ROOT PORTIONS OF SAID THREAD MEANS ON SAID SOCEKT AND SAID CREST PORTIONS OF SAID THREAD MEANS ON SAID STUD EACH DEFINING A RIGHT-CYLINDER, THE DIAMETER OF SAID CYLINDER DEFINED BY SAID ROOT PORTIONS OF SAID THREAD MEANS ON SAID SOCKET BEING SLIGHTLY GREATER THAN THE DIAMETER OF SAID CYLINDER DEFINED BY SAID CREST PORTIONS OF SAID THREAD MEANS ON SAID STUD WHEREBY SAID COMPLEMENTARY THREAD MEANS COACT WITH A SLIGHT RADIAL CLEARANCE, THE WIDTH OF SAID ROOT PORTIONS OF SAID THREAD MEANS ON BOTH SAID SOCKET AND SAID STUD EXCEEDING THE WIDTH OF SAID CREST PORTIONS OF SAID THREAD MEANS WHEREBY SAID COMPLEMENTARY THREAD MEANS COACT WITH A SLIGHT AXIAL CLEARANCE ON ONE SIDE OF CONTIGUOUS THREAD CONVOLUTIONS TO PERMIT SLIGHT AXIAL MOVEMENT UNDER IMPACT WITH- 